9, 10-alpha, alpha-oh-taxane analogs and method for production thereof

ABSTRACT

Provided herein are compounds, compositions containing the compounds, and methods for the treatment of cancer in a cancer patient. In particular, the compounds are made by a process comprising treating a first compound represented by either Formula G′ or Formula M′: 
     
       
         
         
             
             
         
       
     
     with a second compound of generalized formula R 8 R 9 C(OCH 3 ) 2  and an acid selected from the group consisting of camphor sulfonic acid (CSA), p-toluene sulfonic acid (PTSA), hydrochloric acid (HCl) and acetic acid (AcOH), wherein R 1  and R 2  are each selected from H, an alkyl group, an olefinic group, an aromatic group, an O-alkyl group, an O-olefinic group, or an O-aromatic group; R 7  is an alkyl group, an olefinic group, or an aromatic group; P 1  is a hydroxyl protecting group; P 5  is H or an acid labile protecting group at the 7-O position; R 8  is H, alkyl group, olefinic or aromatic group; and R 9  is: H, alkyl group, olefinic or aromatic or is as defined in the specification.

FIELD OF THE INVENTION

The present invention generally relates to chemical compounds for use intreating cancer patients. More particularly, the present invention isdirected to new and useful taxane analogs and methods for producingthem. Specifically, the present invention relates to 9,10-α,α-OH taxaneanalogs, production methods and intermediates useful in the formationthereof.

BACKGROUND OF THE INVENTION

Various taxane compounds are known to exhibit anti-tumor activity. As aresult of this activity, taxanes have received increasing attention inthe scientific and medical community, and are considered to be anexceptionally promising family of cancer chemotherapeutic agents. Forexample, various taxanes such as paclitaxel and docetaxel have exhibitedpromising activity against several different varieties of tumors, andfurther investigations indicate that such taxanes promise a broad rangeof potent anti-leukemic and tumor-inhibiting activity.

One approach in developing new anti-cancer drugs is the identificationof superior analogs and derivatives of biologically active compounds.Modifications of various portions of a complex molecule may lead to newand better drugs having improved properties such as increased biologicalactivity, effectiveness against cancer cells that have developedmulti-drug resistance (MDR), fewer or less serious side effects,improved solubility characteristics, better therapeutic profile and thelike.

In view of the promising anti-tumor activity of the taxane family, it isdesirable to investigate new and improved taxane analogs and derivativesfor use in cancer treatment. One particularly important area is thedevelopment of drugs having improved MDR reversal properties.Accordingly, there is a need to provide new taxane compounds havingimproved biological activity for use in treating cancer. There is also aneed to provide methods for forming such compounds. Finally, there is aneed for methods of treating patients with such compounds for use incancer treatment regimens. The present invention is directed to meetingthese needs.

SUMMARY OF THE INVENTION

According to the present invention then, new and useful chemicalcompounds for use in cancer treatment are provided having the formulas:

When reference is made to compounds throughout this disclosure, possibleR_(x) groups and P_(x) groups contemplated hereby are set forth in thefollowing Table 1:

TABLE 1 R_(x) GROUPS AND P_(x) GROUPS CONTEMPLATED R₁ H, an alkyl suchas an isobutyl group or a tert-butoxyl group, olefinic such as a tiglylgroup, aromatic such as a phenyl group, O-alkyl, O-olefinic, or O-aromatic R₂ H, alkyl such as an isobutyl group, olefinic, aromatic groupsuch as Ph, O- alkyl, O-olefinic, or O-aromatic R₃ hydroxyl or OP₁ R₄hydroxyl or R₇COO R₅ hydroxyl or R₇COO R₆ hydroxyl, OP₂, R₇COO or anether functionality such as an O- methylthiomethyl or other heterosubstituted ethers R₇ alkyl such as a methyl group, olefinic or aromaticR₇COO

R₈ H, alkyl group such as a methyl or ethyl group, olefinic or aromaticgroup R₉ H, alkyl group such as a methyl or ethyl group, olefinic oraromatic or may specifically be:

R₁₀ alkyl group such as a methyl or ethyl group R₁₁ H, alkyl group suchas a methyl or ethyl group, olefinic or aromatic group R₁₂ H, alkylgroup such as a methyl or ethyl group, olefinic or aromatic or mayspecifically be:

R₁₃ H, alkyl group such as a methyl or ethyl group, olefinic or aromaticgroup R₁₄ H, alkyl group such as a methyl or ethyl group, olefinic oraromatic or may specifically be:

P₁ hydroxyl protecting group such as a silyl protecting group, forexample, TBDMS or TES P₂ hydroxyl protecting group such as a silylprotecting group, for example, TES P₃ NH protecting group such ascarbobenzyloxy (CBZ)

Specifically, R₁ may be Ph or tert-butoxyl or tiglyl, R₂ may be Ph orisobutyl, R₆ may be O-methylthiomethyl or other hetero substitutedethers, P₁ may be a silyl protecting group such as TBDMS or TES, and P₂may be a silyl protecting group such as TES. Compounds according to thepresent invention may be monoacylated at C-10, such as when R₅ and R₆are hydroxyl and R₄ is R₇COO, where R₇COO has a formula selected fromthe following structures:

Compounds according to the present invention may alternately be mono-,bis-, or tris-acylated at the 7, 9 and/or 10 positions. For example, R₆may be R₇COO when R₄ and R₅ are hydroxyl; R₄ and R₆ may both be R₇COOwhen R₅ is hydroxyl; or each of R₄, R₅ and R₆ may be R₇COO; where R₇COOis:

Additionally, chemical compounds according to the present invention mayhave the formula:

wherein R₁ through R₄ are as defined in Table 1 above and R₈ and R₉ areeach H, alkyl, olefinic or aromatic. Compounds according to the presentinvention may be monoacylated at C10, such as when R₄ is R₇COO, whereR₇COO is:

R₈ may specifically be H or methyl, and R₉ may specifically be:

Compounds according to the present invention may have an acroline acetalgroup connecting the 7,9-positions. For example, chemical compounds offormula:

are provided wherein R₄ is hydroxyl or CH₃COO.

Another example of the 7,9-acetal linked compounds contemplated have theformulas:

The present invention also provides intermediates for use in formingcompounds useful for cancer treatment, comprising:

wherein R₂, R₄, R₈ and R₉ are as defined in Table 1 above, P₃ is a NHprotecting group such as carbobenzyloxy (CBZ), and R₁₁ and R₁₂ are asdefined in Table 1 above for R₈ and R₉, respectively.

The present invention also provides methods for use in producing taxaneanalogs and derivates thereof for use in cancer treatment. One methodaccording to the present invention comprises providing a startingcompound of formula

and converting the starting compound into a first taxane analog of theformula

wherein:

-   -   R₁ and R₂ are each selected from H, an alkyl group, an olefinic        group, an aromatic group, an O-alkyl group, an O-olefinic group,        or an O-aromatic group;    -   R₇ is an alkyl group, an olefinic group, or an aromatic group;        and    -   P₁ and P₂ are each hydroxyl protecting groups;        The starting compound may be oxidized to form a first        intermediate compound of the formula

The method may further include the step of acylating the first taxaneanalog at the C-10 position to form a second taxane analog of formula

that may thereafter be deprotected, thereby to form a third taxaneanalog of formula:

where R₁, R₂, R₇, P₁ and P₂ are as defined in Table 1 above. Theacylation step may be accomplished using a carboxylic acid R₇COOH,carboxylic acid halide R₇COX, such as an acid chloride, or a carboxylanhydride R₇COOCOR₇. When P₁ and P₂ are silyl protecting groups such asTES or TBDMS, the step of deprotecting the second taxane analog may beaccomplished in a single step using tetrabutylammoniumfluoride (TBAF).Alternatively, the step of deprotecting the second taxane analog mayinclude a first step of deprotecting the second compound at the C-7position thereby to form a fourth taxane analog of formula:

and then deprotecting the 2′O position of the fourth taxane analog toform a fifth taxane analog of formula:

The first step may be accomplished using HF-ACN, and the second step maybe accomplished using HF-pyridine.

Alternatively, instead of acylating the first taxane analog, it may bedeprotected at the 7-O position to form a sixth taxane analog of formula

Thereafter the sixth taxane analog may be acylated at the C-7 position,the C-9 position, or the C-10 position to form a seventh taxane analogof formula

The seventh taxane analog may be deprotected at the 2′O position to forman eight taxane analog of formula

The acylation step of the sixth taxane analog may be accomplished usinga carboxylic acid R₇COOH, carboxylic acid halide R₇COX, such as an acidchloride, or a carboxyl anhydride R₇COOCOR₇. Deprotection of the seventhtaxane analog at the C-2′ position may be accomplished usingtetrabutylammoniumfluoride (TBAF).

Another method according to the present invention comprises providing astarting compound of formula

wherein

-   -   R₁ and R₂ are each selected from H, an alkyl group, an olefinic        group, an aromatic group, an O-alkyl group, an O-olefinic group,        or an O-aromatic group;    -   R₇ is an alkyl group, an olefinic group, or an aromatic group;        and    -   P₁ and P₂ are each hydroxyl protecting groups;

The starting compound may be converted into a first taxane analog offormula

wherein

-   -   R₁ and R₂ are each selected from H, an alkyl group, an olefinic        group, an aromatic group, an O-alkyl group, an O-olefinic group,        and an O-aromatic group;    -   R₃ is hydroxyl or OP₁;    -   R₇=an alkyl group, an olefinic group, or an aromatic group;    -   P₁ is a hydroxyl protecting group.        The first taxane analog may have a formula selected from the        following structures

The first taxane analog may then be protected as a 7,9-acetal linkedanalog to form a second taxane analog of formula

which may specifically have one of the following formulas

The sidechain of the second taxane analog may thereafter be cleaved atthe C-13 position to convert the second taxane analog into a firstintermediate compound of formula

Subsequently, the first intermediate compound may be esterified with asecond intermediate compound of formula

thereby to form a third taxane analog of formula

wherein:

-   -   R₂ is selected from H, an alkyl group, an olefinic group, an        aromatic group, an O-alkyl group, an O-olefinic group, and an        O-aromatic group;    -   R₄ is either hydroxyl or R₇COO;    -   R₇ is an alkyl group, an olefinic group, or an aromatic group;    -   R₈, R₉, R₁₁, and R₁₂ are each selected from H, an alkyl group,        an olefinic group, or an aromatic group; and    -   P₃ is NH protecting group.        Specifically, the R9 and R12 moieties may specifically be

Also, P₃ may specifically be carbobenzyloxy (CBZ).

A further method according to the present invention comprises convertinga first compound of formula:

to a second compound of formula:

protecting the second compound as an N,O-acetal to form a third compoundof formula:

and saponifying the third compound to a fourth compound of formula:

where R₂, R₁₁, R₁₂ and P₃ are as defined in Table 1 above and R₁₀ is analkyl group such as a methyl or ethyl group.

Finally, the present invention contemplates a method of treating cancerin a patient, comprising administering to the patient a pharmaceuticalformulation including a selected concentration of a taxane and apharmaceutically acceptable carrier therefor, wherein the taxane has aformula:

and C-2'S isomers thereof wherein R₁ through R₉ are as defined in Table1 above.

These and other objects of the present invention will become morereadily appreciated and understood from a consideration of the followingdetailed description of the exemplary embodiments of the presentinvention when taken together with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a generalized Scheme 1 for forming 9,10-α,αtaxane analogs according to the present invention;

FIG. 2 is a diagram of a generalized Scheme 2 for forming 9,10-α,αtaxane analogs according to the present invention;

FIG. 3 is a diagram of a generalized Scheme 3 for forming 9,10-α,αtaxane analogs according to the present invention;

FIG. 4 is a diagram of exemplary R₇COO groups for use in Scheme 3;

FIG. 5 is a diagram of a generalized Scheme 4 for forming mono-, bis-and tris-acylated 9,10-α,α taxane analogs according to the presentinvention;

FIG. 6 is a diagram of exemplary R₇COO groups for use in Scheme 4;

FIG. 7 is a diagram of a generalized Scheme 5 for forming 9,10-α,αtaxane analogs according to the present invention;

FIG. 8 is a diagram of a generalized Scheme 6 for forming9,10-α,α-7,9-acetal taxane analogs according to the present invention;

FIG. 9 is a diagram of exemplary compounds formed according to Scheme 6;

FIG. 10 is a diagram of a generalized Scheme 7 for cleaving thesidechain of 9,10-α,α taxane analogs according to the present invention;

FIG. 11 is a diagram of a generalized Scheme 8 for forming a carboxylicacid for use in attaching an alternative taxane sidechain to 9,10-α,αtaxane analogs according to the present invention;

FIG. 12 is a diagram of a generalized Scheme 9 for esterifying thesidechain of FIG. 11 to a 13-hydroxy-9,10-α,α taxane analog according tothe present invention;

FIG. 13 is a diagram of an exemplary 2′-hydroxyl protection ofpaclitaxel according to the present invention;

FIG. 14 is a diagram of an exemplary 10-deacylation of the compoundformed in FIG. 13;

FIG. 15 is a diagram of an exemplary 7-hydroxyl protection of thecompound formed in FIG. 14;

FIG. 16 is a diagram of an exemplary 10-hydroxyl oxidation of thecompound formed in FIG. 15;

FIG. 17 is a diagram of an exemplary 9,10-diketo reduction of thecompound formed in FIG. 16;

FIG. 18 is a diagram of an exemplary 10-acylation of the compound formedin FIG. 17;

FIG. 19 is a diagram of exemplary 7-deprotections of the compoundsformed in FIGS. 17 and 18;

FIG. 20 is a diagram of exemplary 2′-deprotections of the compoundsformed in FIG. 19;

FIG. 21 is a diagram of exemplary 2′,7-deprotections of the compoundsformed in FIGS. 17 and 18;

FIG. 22 is a diagram of exemplary mono-, bis- and tris-acylations of acompound formed in FIG. 19, where R₇COO may be selected from theformulas of FIG. 6;

FIG. 23 is a diagram of an exemplary 2′-protection of a compound formedin FIGS. 20 and 21;

FIG. 24 is a diagram of an exemplary 7-O-methylthiomethylation of thecompound formed in FIG. 23;

FIG. 25 is a diagram of an exemplary 2-deprotection of the compoundformed in FIG. 24;

FIG. 26 is a diagram of an exemplary 7,9-acetalization reaction of acompound formed in FIG. 19;

FIG. 27 is a diagram of an exemplary 2′-deprotection of the compoundformed in FIG. 26;

FIG. 28 is a diagram of an exemplary 7,9-acetalization of a compoundformed in FIGS. 20 and 21;

FIG. 29 is a diagram of an exemplary reaction for cleaving the taxanesidechain of the compound formed in FIG. 28;

FIG. 30 is a diagram of an exemplary reaction for producing an isobutylN-protected ester compound for use in forming an alternative taxanesidechain according to the present invention;

FIG. 31 is a diagram of an exemplary reaction for protecting thecompound formed in FIG. 30 as an anisaldehyde acetal;

FIG. 32 is a diagram of an exemplary reaction for saponifying thecompound formed in FIG. 31 to a carboxylic acid;

FIG. 33 is a diagram of an exemplary reaction for attaching thesidechain compound formed in FIG. 32 to the 13-hydroxy taxane analogformed in FIG. 29;

FIG. 34 is a diagram of an exemplary deprotection and acylation of thecompound formed in FIG. 33; and

FIG. 35 is a diagram of an exemplary 7,9-acetalization of the compoundformed in FIG. 34.

DETAILED DESCRIPTION OF THE INVENTION

Paclitaxel and docetaxel have a formula as follows:

-   -   Paclitaxel: R₁=Ph, R₄=AcO    -   Docetaxel R₁=t-Butoxy, R₄=OH

Of note is the top part of the molecule as illustrated above, which maybe seen to have a 9-keto structure and 10-β hydroxy or 10-β acetylstereochemistry. The present invention provides novel taxane analogshaving a stereochemistry at the C-9 and C-10 OH positions of themolecule. Generally, these compounds have been found to exhibitexcellent inhibition of cell growth against MDR sensitive cancer celllines. For example, the 9,10-α,α hydroxy taxane derivatives discussed inTable 2 exhibit favorable inhibition of cell growth in several of thetested cell lines.

TABLE 2 BIOLOGICAL ACTIVITY DATA OF SELECTED TAXANES Cancer Type & Cellline MDR Tubulin Agent Concentration Inhibition Ovarian Carcinoma +Mutant Paclitaxel 5 ug/mL 55% 1A9PTX10 Ovarian Carcinoma + Mutant TPI287 0.2 ug/mL 85% 1A9PTX10 Ovarian Carcinoma + Mutant TPI 287 0.1 ug/mL51% 1A9PTX10 Ovarian Carcinoma + Mutant TPI 251 0.5 ug/mL 96% 1A9PTX10Ovarian Carcinoma + Mutant TPI 251 0.25 ug/mL 93% 1A9PTX10 Breast CancerMCF-7 + Wild Paclitaxel 40 ug/mL 55% NCI-AR Type Breast Cancer MCF-7 +Wild TPI 287 0.5 ug/mL 80% NCI-AR Type Breast Cancer MCF-7 + Wild TPI287 0.25 ug/mL 47% NCI-AR Type Breast Cancer MCF-7 + Wild TPI 287 0.125ug/mL 37% NCI-AR Type Breast Cancer MCF-7 + Wild TPI 287 0.061 ug/mL 22%NCI-AR Type Breast Cancer MCF-7 + Wild TPI 287 0.031 ug/mL 13% NCI-ARType Breast Cancer MCF-7 + Wild TPI 251 2.0 ug/mL 94% NCI-AR Type BreastCancer MCF-7 + Wild TPI 251 1.0 ug/mL 65% NCI-AR Type Breast CancerMCF-7 + Wild TPI 251 0.5 ug/mL 45% NCI-AR Type Breast Cancer MCF-7 +Wild TPI 285 2.0 ug/mL 85% NCI-AR Type Breast Cancer MCF-7 + Wild TPI285 1.0 ug/mL 51% NCI-AR Type Breast Cancer MCF-7 + Wild TPI 285 0.5ug/mL 41% NCI-AR Type Neuroblastoma SK-N-AS − Wild Paclitaxel 0.1 ug/mL54% Type Neuroblastoma SK-N-AS − Wild TPI 287 0.05 ug/mL 58% TypeSquamous Cell Carcinoma − Wild Paclitaxel 0.05 ug/mL 47% FADU TypeSquamous Cell Carcinoma − Wild TPI 287 0.05 ug/mL 56% FADU Type

Table 2, above, identifies the compounds TPI 287, TPI 285 and TPI 251,which were found to exhibit excellent inhibition of cell growth againstMDR sensitive cancer cell lines. The compounds TPI 287, TPI 285 and TPI251 are discussed in greater detail below and have the followingrespective structures:

As will become apparent from the discussion below, TPI 287 is a mixtureof the compounds identified as Formula 31 and Formula 33, which arediscussed below with respect to FIG. 35. The 2′R isomer of TPI 285 isillustrated, for example, with respect to generalized Formula A in FIG.1 wherein R₁ is a tert-butoxyl group, R₂ is an isobutyl group and R₇ isacetyl. Although not shown in FIG. 1, the 2'S isomer of TPI 285, asshown above, is also contemplated. TPI 251 is illustrated, for example,with respect to generalized Formula Z in FIG. 9 wherein R₈ is H and R₉is ethylene. In addition to the compounds TPI 287, TPI 285, and TPI 251,various other 9,10-α,α hydroxy taxane derivatives have also exhibitedsignificant inhibition against various cancer cell lines.

1. Synthesis of 9,10-α,α-Hydroxy Taxanes

Such compounds may be formed in a number of ways according to thepresent invention. For example, as shown in FIG. 1 (Scheme 1) and FIG. 2(Scheme 2), a 9,10-α,α hydroxy taxane F may be formed directly from astandard taxane A or A′ through various transformations, includingoxidation of a 10-hydroxy taxane D to a 9,10-diketo taxane E andreduction to the 9,10-α,α-hydroxy taxane F. In the compounds shown inSchemes 1 and 2, R₁ and R₂ may each be H, alkyl such as an isobutylgroup or a tert-butyl group, olefinic such as a tigloyl group, aromaticsuch as a phenyl group, O-alkyl, O-olefinic, or O-aromatic; R₇ may bealkyl such as a methyl group, olefinic or aromatic; and P₁ and P₂ mayeach be a hydroxyl protecting group, such as a silyl protecting group,including TBDMS or TES.

Such a process is exemplified in FIGS. 13 through 17. For example, asshown in FIG. 13, paclitaxel of Formula 1 (where R₁=R₂=Ph; R₇=CH₃ ingeneralized formula A of Scheme 1) is first protected at the 2′-hydroxylwith a hydroxyl protecting group such as tert-butyldimethylsilyl(TBDMS). To a 500 mL round bottom flask (RBF) equipped with a magneticstir bar was charged 50.0 g (58.55 mmol) paclitaxel, Formula 1, 13.96 g(204.8 mmol, 3.5 eq.) imidazole, and 26.47 g (175.7 mmol, 3.0 eq.)TBDMS-Cl. The flask was placed under a nitrogen environment and 350 mL(7 mL/g paclitaxel) anhydrous N,N-dimethyl formamide (DMF) was chargedto the flask. The reaction was stirred at room temperature for twentyhours, then was worked up by diluting the reaction solution in 600 mLisopropyl acetate (IPAc) and washing with water until the aqueous washreached pH 7, then with brine. The organic partition was dried overmagnesium sulfate, filtered and then was evaporated to a white foamsolid to yield 66.9 g (93.0 area percent) of unpurified 2′-O-TBDMSpaclitaxel product of Formula 2 (where R₁=R₂=Ph; R₇=CH₃; P₁=TBDMS ingeneralized formula B of Scheme 1). This reaction is nearlyquantitative. There are slight amounts of 2′,7-bis-TBDMS, but this isnot a significant amount.

Next, as shown in FIG. 14, the 10-acetyl group is removed byhydrazinolysis. To a 1 L RBF equipped with a magnetic stir bar wascharged 59.5 g 2′-O-TBDMS paclitaxel of Formula 2 and 600 mL (10 mL/g)IPAc. The solution was stirred to dissolve the 2′-O-TBDMS paclitaxel,then 60 mL (1 mL/g) hydrazine hydrate was charged to the flask and thereaction stirred at room temperature for one hour. The reaction wasworked up by diluting the reaction solution in 1.2 L IPAc and washingfirst with water, then ammonium chloride solution, then again with wateruntil the aqueous wash was pH 7 and lastly with brine. The organicpartition was dried over magnesium sulfate, filtered and evaporated to55.8 g of solid. The solid was redissolved in 3:1 IPAc (1%water):heptane to a concentration 0.25 g/mL total dissolved solids (TDS)and purified on a YMC silica column; the column eluent was monitored forUV absorbance. The fractions were pooled based on HPLC analysis andevaporated to yield 39.3 g (98.6 area percent) of 2′-O-TBDMS-10-deacetylpaclitaxel solid of Formula 3 (where R₁=R₂=Ph; P₁=TBDMS in generalizedformula C of Scheme 1). If the reaction goes too long (beyond 2 h), theproduct begins epimerizing at the C-7 position. Besides decreasing theyield by the formation of the 7-epi degradant, this impurity requiresadding a chromatographic step to remove the impurity.

As illustrated in FIG. 15, the 7-hydroxyl is now protected with aprotecting group such as triethylsilyl (TES). To a 500 mL RBF equippedwith a magnetic stir bar was charged 39.3 g (42.46 mmol)2′-O-TBDMS-10-deacetyl paclitaxel of Formula 3 and 15.6 g (127.4 mmol, 3eq.) DMAP. The flask was placed under nitrogen and 390 mL (10 mL/g)anhydrous dichloromethane (DCM) charged to the flask to dissolve thesolids followed by 14 mL (84.92 mmol, 2 eq.) TES-CI. The reaction wasstirred at room temperature for three hours. The reaction was worked upby evaporating the reaction solution to approximately half its startingvolume and diluting it in 300 mL EtOAc and washing with water and diluteHCl solutions until the pH of the aqueous wash was approximately 7, thenwith brine. The organic partition was dried over magnesium sulfate andevaporated to yield 42.0 g (97.7 area percent) of white solid of Formula4 (where R₁=R₂=Ph; P₁=TBDMS; P₂=TES in generalized formula D of Scheme1). This reaction is nearly quantitative, with a slight amount of7,10-bis-TES and excess silyl compounds in the worked up solids, as withthe 2′-TBDMS protection step above.

Next, oxidation of the 10-hydroxyl yields a 9,10-diketo compound, asexemplified in FIG. 16. To a 1 L RBF equipped with a magnetic stir barwas charged 41.0 g (39.43 mmol) 2′-O-TBDMS-7-O-TES-10-deacetylpaclitaxel of Formula 4, 2.1 g (5.92 mmol, 0.15 eq.) of TPAP, 13.9 g(118.3 mmol, 3 eq.) NMO. The flask was placed under nitrogen and 720 mL(˜20 mL/g) anhydrous DCM charged to the flask to dissolve the solids.The reaction was stirred at room temperature for 22 hours. The reactionwas worked up by concentrating the reaction solution to half its volumeand then drying the reaction contents onto 175 g silica gel (EM Sciences40-63μ). The taxane containing silica was placed on 30 g of clean silicagel (EM Sciences 40-63μ) and the product eluted from the silica with 4 LMTBE. The MTBE was evaporated to yield 37.3 g (93.2 area percent)2′-O-TBDMS-7-O-TES-9,10-diketo paclitaxel of Formula 5 (where R₁=R₂=Ph;P₁=TBDMS; P₂=TES in generalized formula E of Scheme 1).

Finally, reduction of the 9,10-diketo taxane yields the 9,10-α,α-hydroxytaxane, as shown for example in FIG. 17. To a 2 L RBF equipped with amagnetic stir bar was charged 37.3 g (35.9 mmol) protected 9,10-diketopaclitaxel of Formula 5 and 900 mL (˜30 mL/g taxane) of 3:1 EtOH/MeOH.The solution was stirred to dissolve the solids then the flask wasplaced in an ice/water bath and the solution was stirred for 30 minutes.8.1 g (215.7 mmol, 6 eq.) of sodium borohydride (NaBH₄) was charged tothe flask and the reaction stirred in the ice/water bath for five hours.The reaction was worked up by diluting the reaction solution in 1 L IPAcand washing with 4×750 mL water, then with 200 mL brine. The organicpartition was dried over magnesium sulfate. The aqueous washes werereextracted with 500 mL IPAc. The organic reextract solution was washedwith 100 mL brine then dried over magnesium sulfate and combined withthe first organic partition. The IPAc solution was concentrated untilsolids began precipitating out then heptane was added to the solution tocrystallize the protected 9,10-α,α-OH, 9-desoxo,10-deacetyl paclitaxelproduct of Formula 6 (where R₁=R₂=Ph; P₁=TBDMS; P₂=TES in generalizedformula F of Scheme 1). The crystallizing solution was placed in afreezer overnight. Three crystallizations were done on the material, thefirst yielded 4.1 g (95.3 area percent) protected 9,10-α,α-OH,9-desoxo,10-deacetyl paclitaxel product, the second yielded 18.3 g (90.9area percent) product, and the third yielded 2.9 g (81.7 area percent)product. The original work on this reaction employed flashchromatography to purify the product. However, the crystallizations thatwere performed gave similar purity, by HPLC, to the chromatographedmaterial from earlier work.

As illustrated in FIG. 2 (Scheme 2), the same steps as above may befollowed—absent the hydrazinolysis step—when the starting material is a10-deacetyl taxane, such as of generalized Formula A′ in FIG. 2.

II. 10-Acylation and 2′,7-Deprotection

Next, as shown in FIG. 3 (Scheme 3), the resulting taxane of generalizedformula F may be deprotected at the 7-position to yield the taxane ofgeneralized formula H and then deprotected at the 2′-position to yield ataxane of the generalized formula I. The deprotection at the 2′- and7-positions may be either a two-step process or may be performed in asingle step.

Alternatively, as shown in Scheme 3, the taxane of generalized formula Fmay be first acylated at the 10 position before deprotecting at the 7and 2′ positions. According to this route, the 10 acylation of thetaxane of generalized formula F results in the taxane of generalizedformula G, which may then be deprotected at 7 position to yield a taxaneof the generalized formula H′ and deprotected at the 2′-position toyield a taxane of the generalized formula I′. Here again, thedeprotection at the 7- and 2′-positions may be either a two-step processor may be performed in a single step.

The 10-acylation of the taxane of generalized formula F may beaccomplished in a number of manners, as exemplified in FIG. 18. Inparticular, the invention contemplates the use of either a carboxylicacid of generalized formula R₇COOH, a carboxylic acid halide such as anacid chloride of generalized formula R₇COCl, or a carboxyl anhydride ofgeneralized formula R₇COOCOR₇. In the compounds shown in Scheme 3, R₁,R₂, R₇, P₁ and P₂ are as defined above for Schemes 1 and 2, although itshould be appreciated that the R₇COO group attached at C-10 in Scheme 3may be different from the R₇COO group that was removed in Scheme 1.

When the reagent used is a carboxylic acid, an exemplary procedure (asshown in FIG. 18) is as follows. To a 25 mL RBF equipped with a magneticstir bar was charged 300 mg (0.288 mmol) of2′-O-TBDMS-7-O-TES-9,10-α,α-OH, 9-desoxo, 10 deacetyl paclitaxel ofFormula 6 (where R₁=R₂=Ph; P₁=TBDMS; P₂=TES in generalized formula F ofScheme 3), (0.720 mmol, 2.5 eq.) carboxylic acid (CH₃COOH), 178 mg(0.864 mmol, 3.0 eq.) of DCC, and 13 mg (0.086 mmol, 0.3 eq.) of4-pyrrolidinopyridine (4-Pp). The contents of the flask were placed in anitrogen environment and 10 mL anhydrous DCM added to the flask. Thereactions were stirred at room temperature for 15+ hours (all thereactions were monitored by TLC or HPLC for consumption of the startingmaterial); the reactions generally ran overnight. The reactions wereworked up by diluting the reaction solution in 20 mL EtOAc and stirringfor fifteen minutes to precipitate dicyclohexyl urea (DCU). The DCU wasremoved from the solution by vacuum filtration and the filtrate waswashed with water until the pH of the water washes was approximately 7.The organic solution was then washed with brine and dried over sodiumsulfate before evaporating to dryness.

When the reagent used is a carboxylic acid halide, an exemplaryprocedure (as shown in FIG. 18) is as follows. To a 25 mL RBF, equippedwith a magnetic stir bar and under a nitrogen environment, was charged300 mg (0.288 mmol) of 2′-O-TBDMS-7-O-TES-9,10-α,α-OH, 9-desoxo 10deacetyl paclitaxel of Formula 6, (0.720 mmol, 2.5 eq.) acid chloride(CH₃COCl), 1404 (1.008 mmol, 3.5 eq.) TEA, 13 mg (0.086 mmol, 0.3 eq.)4-Pp, and 10 mL anhydrous DCM. The reactions were stirred at roomtemperature for 15+ hours; reactions generally ran overnight and weremonitored by TLC and/or HPLC in the morning for consumption of startingmaterial. The reactions were worked up by diluting the reaction solutionin 20 mL EtOAc and washing with water until the pH of the water washeswas approximately 7. The organic solution was then washed with brine anddried over sodium sulfate before evaporating to dryness.

When the reagent used is a carboxyl anhydride, an exemplary procedure(as shown in FIG. 18) is as follows. To a 25 mL RBF, equipped with amagnetic stir bar and under a nitrogen environment, was charged 300 mg(0.288 mmol) 2′-O-TBDMS-7-O-TES-9,10-α,α-OH, 9-desoxo 10 deacetylpaclitaxel of Formula 6, (2.880 mmol, 10 eq.) acid anhydride(CH₃COOCOCH₃), 106 mg (0.864 mmol, 3 eq.) DMAP, and 5 mL anhydrous DCM.The reactions were stirred at room temperature for 15+ hours. Thereactions were worked up by adding 5 mL saturated sodium bicarbonatesolution to the reaction flask and stirring for 5 minutes. The solutionwas then transferred to a seperatory funnel and organics were extractedwith 20 mL EtOAc. The organic extract was then washed with saturatedsodium bicarbonate and water until the pH of the water washes wasapproximately 7. The organic partition was then washed with brine anddried over sodium sulfate before evaporating to dryness.

The resulting product is the 2′-O-TBDMS-7-O-TES-9-α-OH,9-desoxo,10-epipaclitaxel of Formula 7 (where R₁=R₂=Ph; P₁=TBDMS; P₂=TES; R₇=CH₃ ingeneralized formula G of Scheme 3). FIG. 4 shows numerous alternativegroups that may be used for the R₇COO group at the 10-α-position ofgeneralized formula G. As would be appreciated by the ordinarily skilledperson, these acylations may be performed for example by substitutingthe appropriate carboxylic acid R₇COOH, carboxylic acid halide R₇COX orcarboxyl anhydride R₇COOCOR₇ in the above procedures.

As indicated above and as further illustrated in Scheme 3, taxanes ofgeneralized formula F or G may be deprotected at the 2′- and 7-positionsin either a two-step process or a single step. FIGS. 19 through 21 showexemplary deprotections of the 2′- and 7-positions.

For example, as shown in FIG. 19, the 7-O-TES group may be removed fromFormula 6 to give Formula 8 (where R₁=R₂=Ph; P₁=TBDMS in generalizedformula H of Scheme 3) or from Formula 7 to give Formula 9 (whereR₁=R₂=Ph; P₁=TBDMS; R₇=CH₃ in generalized formula H′ of Scheme 3),respectively, using acetonitrile (ACN) and aqueous HF. To a 500 mLteflon bottle equipped with a magnetic stir bar was charged 2.50 g (2.40mmol) 2′-O-TBDMS-7-O-TES-9,10-α,α-OH, 9-desoxo,10deacetyl paclitaxel ofFormula 6 and 100 mL ACN. The bottle was placed in and ice/water bathand the solution was stirred for 30 minutes. Next, 0.8 mL of 48% HFaqueous was added slowly to the reaction solution and the reactionstirred in the ice/water bath for 20 minutes. The reaction was monitoredby TLC for disappearance of the starting material. The reaction wasworked up by diluting the reaction solution by adding 200 mL EtOAc andquenching the acid by adding 25 mL saturated sodium bicarbonate solutionto the bottle and stirring for 10 minutes. The solution was thentransferred to a separatory funnel and the organic partition was washedwith water until the pH of the water wash was approximately 7, then waswashed with brine. The organic partition was dried over sodium sulfateand then was evaporated to a solid of Formula 8. This procedure was alsofollowed if there was an acyl group on the 10-α-hydroxyl (i.e. Formula 7to Formula 9 in FIG. 19 or generalized formula G to generalized FormulaH′ in Scheme 3).

Next, as shown in FIG. 20, the 2′-O-protecting group may be removed fromFormula 8 to give Formula 10 (where R₁=R₂=Ph in generalized formula I ofScheme 3) or from Formula 9 to give Formula 11 (where R₁=R₂=Ph; R₇=CH₃in generalized formula I′ of Scheme 3), respectively. To a 50 mL teflonbottle equipped with a magnetic stir bar was charged, 500 mg2′-O-TBDMS-9,10-α,α-OH, 9-desoxo, 10-deacetyl paclitaxel of Formula 8(or 2′-O-TBDMS-9-α-OH, 9-desoxo,10-epi paclitaxel of Formula 9) and 5 mLanhydrous THF. Next, 1 mL HF-pyridine solution was slowly charged to thereaction solution. The reaction was stirred at room temperature for 1hour; reaction progress was monitored by TLC and/or HPLC fordisappearance of starting material. The reaction was worked up by adding10 mL EtOAc to the bottle to dilute the reaction solution then saturatedsodium bicarbonate was slowly added to the bottle to neutralize the HF.The solution was then transferred to a separatory funnel and the organicpartition was washed with 10 wt % sodium bicarbonate solution then wateruntil the pH of the water wash was approximately 7. Then the organicpartition was washed with brine and then dried over sodium sulfatebefore evaporating to a solid of Formula 10 (or Formula 11).

It should be appreciated that one ordinarily skilled in the art wouldunderstand that the order of the above deprotection steps may bereversed, such that the 2′-hydroxyl protecting group is removed first,and the 7-hydroxyl protecting group removed second.

Further, as indicated above, the 2′- and 7-positions of either thetaxanes of the generalized formula F or G may be deprotected in aone-step procedure using tetrabutylammoniumfluoride (TBAF). Here, asshown for example in FIG. 21, Formula 6 may be deprotected directly toFormula 10, and Formula 7 may be deprotected directly to Formula 11. A10 mL RBF equipped with a magnetic stir bar was charged with 100 mg of2′-O-TBDMS-7-O-TES-9,10-α,α-OH, 9-desoxo 10 deacetyl paclitaxel ofFormula 6 (or 2′-O-TBDMS-7-O-TES-9-α-OH-10-epi paclitaxel of Formula 7)and 5 mL EtOAc or THF to dissolve the taxane. Next, 100 μL of 1M TBAF inTHF was charged to the flask and the reaction was stirred at roomtemperature for 1 hour; the reaction was monitored by TLC and/or HPLCfor disappearance of starting material. The reaction was worked up bywashing the reaction solution with water and then brine. The organicpartition was dried over sodium sulfate and evaporated to a solid ofFormula 10 (or Formula 11). This method removes both the 2′-O-TBDMSprotecting group and the 7-O-TES protecting group.

III. 7,9,10-Acylation

Now, as illustrated in FIG. 5 (Scheme 4), the 7-, 9-, and/or10-positions may be acylated with various groups R₇COO, such as thoseshown in FIG. 6. In the compounds shown in Scheme 4, R₁, R₂, R₇, and P₁are as defined above for Schemes 1 and 2, although it should beappreciated that the R₇COO groups in Scheme 4 may be different from theR₇COO group that was removed in Scheme 1. For example, as shown in FIG.22, 2′-O-TBDMS-9,10-α,α-OH, 9 desoxo, 10 deacetyl paclitaxel of Formula8 (where R₁=R₂=Ph; P₁=TBDMS in generalized formula H of Scheme 4) may bemono-acylated on the 7-hydroxyl as Formula 12 (corresponding togeneralized formula J of Scheme 4), bis-acylated on the 7,10-hydroxylsas Formula 13 (corresponding to generalized formula J′ of Scheme 4),and/or tris-acylated on the 7,9,10-hydroxyls as Formula 14(corresponding to generalized formula J″ of Scheme 4). It should beappreciated by the ordinarily skilled person that the appropriatecarboxylic acid R₇COOH corresponding to the desired R₇COO group may besubstituted in the procedure below, such as those groups from FIG. 6 orother groups as desired. To a 5 mL RBF, equipped with a magnetic stirbar and nitrogen purge, was charged 100 mg (0.108 mmol)2′-O-TBDMS-9,10-α,α-OH, 9 desoxo, 10 deacetyl paclitaxel of Formula 8,(0.324 mmol, 3 eq.) carboxylic acid, 66.8 mg (0.324 mmol, 3 eq.) DCC,6.6 mg (0.054 mmol, 0.5 eq.) DMAP, and 1.5 mL anhydrous DCM. Thereaction was stirred at room temperature for 2.5 hours. The reactionprogression was monitored by TLC and/or HPLC. If no acyl addition wasdetected, an additional charge of reagents was done to try and start thereaction. The reaction produces a mixture of monoacylated, bisacylated,and some trisacylated products. The reaction was worked up by filteringthe reaction solution through a 0.2 μm nylon acrodisc. To the filtrateplus a 1 mL DCM wash of the solids 100 mg of IRC-50 ion-exchange resinwas added. The mixture was stirred at room temperature for 30 minutes.The mixture was filtered again through a second 0.2 μm nylon acrodisc.As further shown in FIG. 22, the resulting filtrate solution wentdirectly to the reaction to remove the TBDMS from the 2′-hydroxyl usingthe TBAF method, described above to obtain formula 10 and formula 11from formula 6 and formula 7 respectively; 1504 of the reagent was addeddirectly to the filtrate and stirred at room temperature for four hours.The work-up was the same as described above for the deprotection method.Compounds were purified on a reverse phase semi-prep scale HPLC columnto provide Formula 15 (corresponding to generalized formula K of Scheme4), Formula 16 (corresponding to generalized formula K′ of Scheme 4) andFormula 17 (corresponding to generalized formula K″ of Scheme 4).

IV. 7-Ether Functionality

As illustrated in FIG. 7 (Scheme 5) the 2′-hydroxyl may be protected anda functional group attached at the C-7 position, as shown for example inFIGS. 23 through 25. In the compounds shown in Scheme 5, R₁, R₂, R₇, andP₁ are as defined above for Scheme 3, and R₆ is an ether functionality,such as an O-methylthiomethyl group or other hetero substituted etherfunctionalities. Initial attempts to synthesize a 7-O-methylthiomethylcompound from 2′-O-TBDMS-9-α-OH-10-epi paclitaxel provided difficulty inthat the methylthiomethyl group was too labile to withstand the2′-hydroxyl deprotection step using either the HF-pyridine method or theTBAF method, described above. Accordingly, it is desirable to use a2′-hydroxyl protecting group that can be removed under less harshconditions, such as a TES protecting group. In FIG. 23, 9-α-OH-10-epipaclitaxel of Formula 11, which may be formed according to one of theroutes described above with respect to Scheme 3, is first protected asthe 2′-O-TES ether of Formula 18 (where R₁=R₂=Ph; P₁=TES; R₇=CH₃ ingeneralized formula L of Scheme 5). To a 25 mL RBF, equipped with amagnetic stir bar and a nitrogen purge, was charged 1.2 g (1.415 mmol)9-α-OH-10-epi paclitaxel of Formula 11, 6 mL anhydrous DCM, and 6 mLanhydrous pyridine. The flask was placed in an ice/water bath and thesolution was stirred for 15 minutes. After the solution cooled, 0.95 mL(5.659 mmol, 4.0 eq.) TES-Cl was charged to the flask. The reaction wasstirred in the ice/water bath for 3 hours. The reaction was worked up bydiluting the reaction solution in 30 mL EtOAc and washing with waterthen brine. The organic partition was dried over sodium sulfate beforeevaporating to a solid. The 2′-O-TES-9-α-OH-10-epi paclitaxel product ofFormula 18 was purified by flash chromatography using an EtOAc/heptanegradient.

As shown for example in FIG. 24, a methylthiomethyl group may beattached at the 7-O-position to give Formula 19 (where R₁=R₂=Ph; P₁=TES;R₇=CH₃; R₆=OCH₂SCH₃ in generalized formula M of Scheme 5). Because theC-9 hydroxyl is very susceptible to oxidation, it is preferred thatthere are no oxidizing reagents present in the reaction to add themethylthiomethyl ether to the modified taxane. A 100 mL RBF was equippedwith a magnetic stir bar, a nitrogen purge, and a condenser, and waswrapped with aluminum foil. 850 mg (0.877 mmol) 2′-O-TES-9-α-OH-10-epipaclitaxel of Formula 18, 894 mg (5.261 mmol, 6 eq.) silver nitrate, 156mg (1.052 mmol, 1.2 eq.) 4-Pp, 50 mL anhydrous toluene, and 0.8 mL(5.701 mmol, 6.5 eq.) TEA were charged to the flask. The solution wasstirred to dissolve the solids then 441 μL (5.261 mmol, 6.0 eq.)chloromethylmethyl-sulfide was charged to the flask. The reaction washeated to 70° C. The reaction was stirred at 70° C. for 24 hours. Thereaction was worked up by filtering the reaction solution throughCelite. The reaction flask and solids were washed with 80 mL EtOAc. Thecombined filtrate was transferred to a separatory funnel and washed withwater then dilute ammonium chloride then dilute sodium bicarbonate thenwith water until the pH of the water wash was approximately 7. Next theorganic partition was washed with brine then dried over sodium sulfatebefore it was concentrated to approximately 5 mL. This solution waspurified by flash chromatography using an EtOAc/heptane gradient. Thefraction pools were evaporated to yield 0.13 g of2′-O-TES-7-O-methylthiomethyl-9-α-OH-10-epi paclitaxel of Formula 19.

The 2′-hydroxyl is then deprotected, as shown for example in FIG. 25 toprovide Formula 20 (where R₁=R₂=Ph; R₇=CH₃; R₆=OCH₂SCH₃ in generalizedformula N of Scheme 5). To a 10 mL RBF, equipped with a magnetic stirbar, 0.12 g (0.117 mmol) 2′-O-TES-7-O-methylthiomethyl-9-α-OH-10-epipaclitaxel of Formula 19 and 8 mL ACN were charged. The flask was placedin an ice/water bath and the solution stirred for 30 minutes. 233 μL(0.233 mmol, 2 eq.) of 1N HCl was charged to the flask and the reactionstirred in the ice/water bath for 45 minutes. The methylthiomethyl etheris fairly acid labile, and the methylthiomethyl group may be removed ifthe reaction to remove the TES group using 1N HCl in ACN runs too long.The reaction was worked up by pouring the reaction solution into aseparatory funnel containing 20 mL EtOAc and 30 mL saturated sodiumbicarbonate solution. After agitation the aqueous partition was removedand the organic partition was washed with water until the pH of thewater wash was approximately 7 then with brine. The organic partitionwas dried over sodium sulfate then evaporated to a yellowish oil. Theproduct was purified by reverse phase semi-prep scale HPLC to yield 50mg of 7-O-methylthiomethyl-9-α-OH-10-epi paclitaxel of Formula 20 as awhite solid.

V. 7,9-Acetal Linked Analogs

As illustrated in FIG. 8 (Scheme 6) the present invention also provides7,9 acetal linked analogs of 9,10-α,α OH taxanes. In particular, the 7-and 9-positions may be linked through a generalized —OC(R₈)(R₉)O—structure and the 2′-position may be deprotected. In the compounds shownin Scheme 6, R₁, R₂, R₇ and P₁ are as defined above for Scheme 3, and R₈and R₉ may each be H, alkyl, olefinic or aromatic. FIG. 9 illustratesvarious 7,9-acetal linked analogs of formula Z formed according to themethod described below. Initial data from a cytotoxicity study on thecompound where R₈=R₉=H in FIG. 9 suggested that there was good activityfor the acetal. It should be appreciated that the present inventioncontemplates further variations in the substituents of such 7,9-acetallinked analogs. For example, the R₈ and R₉ groups shown in FIG. 9, orothers, may be substituted for R₈ and R₉ in the generalized formulas Oand P of Scheme 6, and the R₁, R₂, R₇ and P₁ groups thereof may befurther varied as described herein.

For example, as shown in FIG. 26, a compound of Formula 9 (which may beformed as described above with respect to FIG. 19) may be protected as a7,9-acetal linked analog of Formula 21 (where R₁=R₂=Ph; P₁=TBDMS;R₇=CH₃; R₈=R₉=H in generalized formula O of Scheme 6). To a 10 mL RBF,equipped with a magnetic stir bar and nitrogen purge, 100 mg (0.103mmol) 2′-O-TBDMS-9-α-OH-10-epi paclitaxel of Formula 9, 2.5 mg (0.013mmol, 0.13 eq.) p-toluene sulfonic acid, and 5 mL anhydrous DCM wereadded. The solution was stirred to dissolve the solids then CH₂(OCH₃)₂(0.515 mmol, 5 eq.) was added and the reaction was stirred at roomtemperature for 1.5 hours. Reaction progress was monitored by TLC and/orHPLC. The reaction was worked up by diluting the reaction solution in 10mL and washing the resulting solution with water then brine. The organicpartition was dried over sodium sulfate and evaporated to a solid ofFormula 21. The protected product was purified on a reverse phasesemi-prep scale HPLC before running the TBAF deprotection method, asshown in FIG. 27, to remove the TBDMS group to form Formula 22 (whereR₁=R₂=Ph; R₇=CH₃; R₈=R₉=H in generalized formula 0 of Scheme 6). Asapparent from Scheme 6, it should be appreciated that compounds ofgeneralized formula R₈R₉C(OCH₃)₂ may be substituted in the reactionabove to provide 7,9-acetal linked analogs having R₈ and R₉ groups, suchas those illustrated in FIG. 9 or others.

VI. Replacement of Taxane Sidechain

The discussion above and the corresponding figures illustrate variousmethods of producing 9,10-α,α-OH taxanes as well as intermediatecompounds useful in the formation of those taxanes. With respect tothose 9,10-α,α-OH taxanes produced by those methods, the sidechain maybe cleaved therefrom so as to attach an alternative sidechain havingdifferent substituents than those shown and described. Accordingly, FIG.10 provides a generalized Scheme 7 for cleaving the sidechain of9,10-α,α-OH taxane analogs according to the present invention. Thesidechain may be replaced, for example, with a compound of Formula 12according to the generalized Scheme 9, shown in FIG. 12.

More particularly, as shown in Scheme 7 and exemplified in FIGS. 28 and29, a 9,10-α,α-taxane may be protected as a 7,9-acetal linked analog,such as described above, and the sidechain may thereafter be cleaved toprovide a 13-hydroxyl taxane. In the compounds shown in Scheme 7, R₃ ishydroxyl or OP₁; R₁, R₂, R₇ and P₁ are as defined above for Scheme 3;and R₈ and R₉ are as defined above for Scheme 6.

For example, a compound of Formula 11 was first prepared according toprocedures described above with respect to FIGS. 18 and 21, as follows.To a 200 mL RBF was charged 5.0 g (4.800 mmol)2′-O-TBDMS-7-O-TES-9,10-α,α-OH, 9 desoxo 10 deacetyl paclitaxel (Formula6), 1.75 g (14.400 mmol, 3.0 eq.) DMAP, and 60 mL anhyd. DCM to dissolvethe solids. The flask was sealed and placed under nitrogen then theflask was placed in an ice-water bath. Next was slowly charged, 4.5 mL(48.000 mmol, 10.0 eq.) acetic anhydride to the flask. The reaction wasstirred at 0° C., going to room temperature overnight. The reaction wasquenched after 18 hours by adding 100 mL of saturated sodium bicarbonatesolution. Product was extracted with EtOAc and washed with sodiumbicarbonate solution and with water. The organic partition was drieddown to yield approximately 5.5 g (5.075 mmol) of crude product ofFormula 7. This crude product was charged in a 250 mL RBF with 110 mLTHF, under nitrogen. Next was charged 14.2 mL of 1.0M TBAF in THF. Thereaction was stirred at room temperature for 2.5 hours then was workedup by extracting with EtOAc and washing with water. The organicpartition was evaporated to yield approximately 5.9 g of crude solid.The crude material was purified by flash chromatography to yield 1.5 gof purified compound of Formula 11.

As shown for example in FIG. 28, the compound of Formula 11 may beprotected as a 7,9-acetal such as with anisaldehyde dimethyl acetal toform a compound of Formula 23 (where R₁=R₂=Ph; R₃=OH; R₇=CH₃; R₈=H;R₉=PhOMe in generalized formula Q of Scheme 7). To a 50 mL RBF wascharged 1.15 g (1.345 mmol) 9-α-OH-10-epi paclitaxel of Formula 11 and25 mL anhydrous DCM, under nitrogen. 343 μL (2.017 mmol, 1.5 eq.)anisaldehyde dimethyl acetal was charged to the flask, followed by 51 mg(0.269 mmol, 0.2 eq.) PTSA. The reaction was stirred at room temperaturefor 45 minutes then was worked up by extracting the product with EtOAcand washing with saturated sodium bicarbonate solution followed bywater. The organic partition was evaporated to yield approximately 1.5 gof crude product. The crude product was purified by flash chromatographyto yield 0.72 g of pure product of Formula 23.

Next, the sidechain is cleaved to form the compound of Formula 24 (whereR₇=CH₃; R₈=H; R₉=PhOMe in generalized formula R of Scheme 7), asexemplified in FIG. 29. To a 25 mL RBF was charged 720 mg (0.740 mmol)7,9-anisaldehyde acetal-10-epi paclitaxel of Formula 23 and 15 mL anhyd.THF, under nitrogen. The flask was placed in an ice/water/ammoniumchloride, −13° C. bath. Solid lithium borohydride (29.0 mg, 1.331 mmol,1.8 eq.) was charged to the reaction flask and the reaction stirred at−13° C. for two hours before raising the temperature to 0° C. Thereaction was worked up after five hours fifteen minutes by diluting withEtOAc and washing with water and ammonium chloride solution. The organicpartition was evaporated to yield 650 mg of crude compound but HPLCindicated that there was only approximately 20% product and mostlyunreacted starting material; therefore, the reaction was restarted byrepeating the above procedure and running the reaction for an additionalsix hours. The organic partition was evaporated to yield approximately660 mg of crude product. The compound was purified on a YMC silicacolumn to yield the compound of Formula 24.

The replacement sidechain may next be formed as illustrated in FIG. 11(Scheme 8) and shown in FIGS. 30 through 32, for example. In thecompounds shown in Scheme 8, R₂ is as defined above for Schemes 1 and 2;P₃ is a hydroxyl protecting group such as a carbobenzyloxy (CBZ) group;R₁₀ is an alkyl group such as a methyl or ethyl group; and R₁₁ and R₁₂are defined as for R₈ and R₉, respectively, for Scheme 6 above. Itshould be appreciated that the R₂ group attached at C-3 in Scheme 8 maybe different from the R₂ group that was on the sidechain that wasremoved in Scheme 7. Further, while the exemplary diagrams show anisobutyl sidechain, it should be appreciated that other groups may besubstituted for the various substituents in the formulas of Scheme 8.

As shown in FIG. 30, a carboxylic acid of Formula 25 (whereR₂=CH₂CH(CH₃)₂ in generalized formula S of Scheme 8) is converted to anester of Formula 26 (where R₂=CH₂CH(CH₃)₂; P₃=CBZ; R₁₀=methyl ingeneralized formula T of Scheme 8). To a 1 L RBF was charged 8.65 g(53.69 mmol) 2-R,S-hydroxy-3-S-amino-5-methyl hexanoic acid of Formula25, and 130 mL MeOH to suspend the acid. The flask was then placed in anice-water bath and 17.6 mL (241.62 mmol, 4.5 eq.) thionyl chloride(SOCl₂) was slowly charged to the flask. The reaction was stirred at 0°C. for four and a half hours then 160 mL EtOAc and 100 mL water wascharged to the flask and the pH of the reaction solution was adjusted toapproximately 8 using 3M NaOH. Next, 16.9 mL (118.1 mmol, 2.2 eq.)CBZ-Cl was charged to the flask and the pH was then readjusted toapproximately 8. The reaction was stirred an additional three hoursbefore working it up by diluting the reaction with EtOAc, removing theaqueous partition and washing the organic solution with water beforeevaporating it to yield approximately 22 g of crude oil. The product waspurified by normal phase chromatography to yield 8.4 g of product ofFormula 26.

As shown in FIG. 31, the compound of Formula 26 may be protected as anN,O-anisaldehyde acetal of Formula 27 (where R₂=CH₂CH(CH₃)₂; P₃=CBZ;R₁₀=methyl; R₁₁=H; R₁₂=PhOMe in generalized formula U of Scheme 8). To a10 mL RBF equipped with a reflux condenser was charged 250 mg (0.809mmol) 2-R,S-hydroxy-3-S—N-(Cbz)-5-methyl hexanoyl methyl ester and 6 mLtoluene to dissolve the solid. Next was charged 15 mg (0.081 mmol, 0.1eq.) PTSA followed by 1654 (0.970 mmol, 1.2 eq.) anisaldehyde dimethylacetal. The reaction was refluxed for two and a half hours then wasquenched by washing the reaction solution with 4 mL of saturated sodiumbicarbonate solution. The organic partition was evaporated to an oilthen was purified by flash chromatography to yield 218 mg of product ofFormula 27.

While it is preferred that the N,O-acetal protecting the sidechain isthe same as the 7,9-acetal protecting the taxane backbone (i.e. R₈=R₁₁and R₉=R₁₂) so that they may both be removed later in a single chemicalstep, it should be appreciated that different acetal protecting groupsmay be used, and separate deprotection steps may be necessary.

As shown in FIG. 32, the ester compound of Formula 27 is next saponifiedto its corresponding carboxylic acid of Formula 28 (whereR₂=CH₂CH(CH₃)₂; P₃=CBZ; R₁₁=H; R₁₂=PhOMe in generalized formula V ofScheme 8). To a 5 mL RBF was charged 280 mg (0.656 mmol) of3-N,2-O-anisaldehyde acetal-3-N-Cbz-5-methyl hexanoyl methyl ester ofFormula 27 and 2.8 mL EtOH to dissolve the solid. Next was charged asolution of 51.3 mg LiOH monohydrate in 420 μL water. The reaction wasstirred at room temperature for four hours and fifteen minutes then wasworked up by quenching with dilute HCl to pH 1 and extracting theproduct into 20 mL toluene. The organic phase was then washed with waterand evaporated to 216 mg of acid product of Formula 28.

As shown in Scheme 9, the replacement sidechain is next coupled to thetaxane backbone. In the compounds shown in Scheme 9, R₂, R₁₁, R₁₂ and P₃are as defined above for Scheme 8; R₇, R₈ and R₉ are as defined abovefor Scheme 7; R₁ is as defined above for Schemes 1 and 2; and R₁₃ andR₁₄ are as defined above for R₈ and R₉, respectively, of Scheme 6. Itshould be appreciated that the R₁ group in Scheme 9 may be differentfrom the R₁ group that was on the sidechain that was removed in Scheme7.

FIG. 33, for example, provides the coupling reaction of Formula 24 (fromFIG. 29) with Formula 28 (from FIG. 32) to provide the compound ofFormula 29 (where R₂=CH₂CH(CH₃)₂; P₃=CBZ; R₁₁=H; R₁₂=PhOMe; R₇=CH₃;R₈=H; R₉=PhOMe in generalized formula W of Scheme 9). To a 5 mL RBF wascharged 180 mg (0.255 mmol) 7,9-anisaldehyde acetal, 9-desoxo 10-epiBaccatin III (Formula 24) and 105 mg (0.510 mmol, 2.0 eq.) DCC. Toluene(2 mL) was then added to dissolve the solids. Next, 158 mg (0.383 mmol,1.5 eq.) iso-Butyl sidechain acid (Formula 28) was dissolved in 1.0 mLDCM then this solution was charged to the reaction flask followed by 6mg (0.038 mmol, 0.15 eq.) 4-pp. The reaction was stirred at roomtemperature for 23 hours then was quenched by adding 11.54 acetic acidand 4 μL water and stirring for one hour. MTBE was added to the reactionflask to precipitate DCU and the reaction solution was filtered toremove the precipitate. The filtrate was slurried with activated carbonthen passed across a silica plug to remove the 4-Pp salts. The eluentwas evaporated to a solid to yield 270.7 mg of crude coupled product ofFormula 29.

As exemplified in FIG. 34, the 7,9-acetal and N,O-acetal protectinggroups may then be removed and an N-acyl group added to form thecompounds of Formula 30 and 32 (where R₁=t-butoxyl; R₂=CH₂CH(CH₃)₂;R₇=CH₃ in generalized formula X of Scheme 9), which may be separatedfrom each other by liquid chromatography or kept together for the nextstep. While the same anisaldehyde group is used at both the 7,9-acetaland N,O-acetal in the exemplary compound of Formula 29, such that bothgroups may be removed in a single step, it should be appreciated thatother acetal protecting groups are contemplated such that multipledeprotection steps may be required. To a 10 mL RBF was charged, 270 mg(0.245 mmol) of 7,9-anisaldehydeacetal-10-epi-3′-isobutyl-3′,2′-N,O-anisaldehyde acetal coupled ester ofFormula 29, 220 mg (0.8 g/g coupled ester) Degussa type palladium oncarbon, and 4.1 mL THF. In a separate vial, 99 μL conc. HCl was dilutedin 198 μL water and 1.0 mL THF. This solution was added to the reactionflask and the flask was sealed and placed under hydrogen. Thehydrogenation reaction was stirred for 31 hours then was quenched byremoving the hydrogen and filtering the catalyst from the reactionsolution then adding molecular sieves to the reaction solution to removewater before adding 84.5 μL (0.368 mmol, 1.5 eq.) t-butoxy carbonyl(t-BOC) anhydride then 684 μL TEA. The reaction stirred an additional 21hours then was worked up by filtering the sieves from the reactionsolution, diluting the filtrate with EtOAc and washing with water. Theorganic partition was evaporated to approximately 370 mg of oil. The oilwas purified first by flash chromatography, then preparative TLC (pTLC)then by a semi-prep reverse phase column to yield 3.9 mg of pure productof Formula 30 and 32.

Finally, as shown in FIG. 35, an alternate 7,9-acetal may be formed ifdesired to provide the compound of Formula 31 or 33 (where R₁=t-butyl;R₂=CH₂CH(CH₃)₂; R₇=CH₃; R₁₃=H; R₁₄=CH═CH₂ in generalized formula Y ofScheme 9). While an acrolein acetal is formed in FIG. 35, it should beappreciated that other groups may be substituted for R₁₃ and R₁₄ ofScheme 9, such as those defined for the R₈ and R₉ groups exemplified inFIG. 9, or others. In a HPLC vial insert, 3.4 mg (4.13 μmol) of9-α-hydroxy, 10-α-acetyl-2′-R,S-hydroxy-3′-S-isobutyl-3′-N-t-butoxycarbonyl taxane of Formula 30 and 32 was charged followed by 70 μL DCM.Next, 12.8 μmol of a 1 to 20 diluted acrolein dimethyl acetal in DCM(0.64 μL acetal, 5.37 μmol, 1.3 eq.) was charged to the insert followedby 8.44 (0.413 μmol, 0.1 eq.) of a 0.05M PTSA solution in DCM. Thereaction was lightly agitated then sat at room temperature. The reactiontook more additions of the acetal solution to drive it to completionthen was worked up after a couple of days by filtering the solutionthrough approximately 80 mg of basic activated alumina. The alumina waswashed with DCM then EtOAc and the fractions evaporated to dryness. Thecrude compound was purified on a normal phase analytical column to yield605 μg of compound (the product was an isomeric mixture) 7,9-acroleinacetal-10-α-acetyl-2′-R,S-hydroxy-3′-S-isobutyl-3′-N-t-butoxy carbonyltaxane of Formulas 31 and 33, which may be separated by liquidchromatography.

VII. Alternative Method for Synthesizing 7,9-Acetal Linked Analogs

7,9 acetal linked analogs of 9,10-αα OH taxanes can also be formeddirectly from 10-deacetylbaccatin III (10-DAB), which has the formula:

Using 10-DAB has an advantage since it is much more naturally abundant,and thus less expensive than either of the starting compounds A or A′that are shown and discussed above with respect to in FIGS. 1 and 2.

In this alternative process, 10-DAB, Formula 34, is first protected atboth the C-7 and C-10 positions to form C7,C10 di-CBZ10-deacetylbaccatin III, Formula 35, according to the followingreaction:

C7,C10 di-CBZ 10-deacetylbaccatin III of Formula 34 (50 g, 91.8 mmol)was dissolved in THF (2 L, 40 ml/g) by warming to 40° C. in a warm-waterbath. The solution was cooled to −41° C. in a Neslab chiller andbenzylchloroformate (46 mL, 3.2 eq, 293.8 mmol) was added to the stirredchilled solution followed by further cooling to −44° C. To this solution2.3M hexyl lithium solution (130 mL, 3.3 eq, 303 mmol) was addedgradually over 45 min while maintaining the temperature of the reactionmixture at ≦−39° C. Stirring continued in the Neslab for 45 minutes atwhich time HPLC indicated the reaction had gone to completion. At 2 hrtotal reaction time, the reaction was quenched by the addition of 1N HCl(400 mL) and IPAc (1 L) and removal from the Neslab chiller. Thereaction was allowed to stir while warming to 10° C. The layers wereseparated and the IPAc layer was washed sequentially with H₂O (500 mL),saturated NaHCO₃ (200 mL) and H₂O (4×500 mL) and then filtered through asilica gel pad. The filtrate was concentrated until solids started toform. IPAc (850 mL) was added and the mixture was heated to 60° C. todissolve some of the solids. To the warm solution, heptanes (800 mL)were added and the solution was cooled in the refrigerator and filtered.The solids collected by the filtration were washed with heptanes anddried under vacuum at 45° C. to give 35.

Next, Formula 35 was coupled with a sidechain of Formula 36 to formFormula 37 according to the following reaction:

Here, the sidechain of Formula 36, (38 g, 99.6 mmol) was dissolved intoluene to a known concentration (0.09524 g/mL). This solution was addedto Formula 35 (54.0 g, 66.4 mmol). The solution was heated in awarm-water bath and DMAP (8.13 g, 66.4 mmol) and DCC (25.28 g, 119.6mmol) in toluene (540 mL) were added to the warm reaction mixture. Whilemaintaining the temperature at about 51° C., the reaction wascontinually stirred and sampled periodically for HPLC. After 3 hours,additional DCC (13.0 g) in toluene (140 mL) was added.

The following morning (25.25 hr), MTBE (450 mL) was added and thereaction mixture was filtered through a pad of silica gel, washed withMTBE followed by EtOAc, and concentrated to give 61.8 g oil. The silicawas washed again with EtOAc and the second pool was concentrated to 50mL and allowed to sit. The following day the second pool had started tocrystallize. It was filtered and the filtrate was washed with 1:1heptane/IPAc and dried under vacuum at 40° C. to give a solid of Formula37.

Next, Formula 37 was deprotected at both the C7 and C10 position to giveFormula 38 according to the following reaction:

A solution of THF (300 mL) and HCl (22 mL) was added to a solution ofFormula 37 (61.8, 52.5 mmol) in THF (15 mL/g, 920 mL). The resultingsolution was flushed with nitrogen. A catalyst (10% Pd/C with 50% water,99.1 g) was added and the flask was flushed with nitrogen three timesand then with hydrogen three times. The reaction mixture was stirredvigorously under a hydrogen balloon for 21 hours. At this time thereaction was sampled and HPLC indicated that 38% by area of startingmaterial still remained. Water (10 mL) was added and stirring continued.Twenty hours later, HPLC indicated the same amount of starting materialstill remaining. The reaction mixture was filtered through celite andwashed with THF. It was then concentrated to remove excess THF; freshcatalyst (101 g) was added and the reaction mixture was placed backunder hydrogen as before. After another 24 hours, an intermediatecompound was still present and still more catalyst (20 g) was added.After another hour, HPLC indicated that the reaction was complete. Thereaction mixture was filtered through celite and washed through withIPAc. The combined filtrate was washed with NH₄Cl solution (500 mL),water (500 mL), 5% NaHCO₃ (500 mL), H₂O (300 mL), and brine (300 mL).The organic layer was dried, filtered, and concentrated to give a foamof Formula 38.

Formula 38 was then converted to Formula 39 according to the followingreaction:

Formula 38 (41.37 g, 52.5 mmol) was dissolved in DCM (500 mL) at roomtemperature. The solution was cloudy, possibly caused by the presence ofDCU in the product from the previous reaction. In the case that theimpurity was water, Na₂SO₄ was added to the solution, and the solutionwas filtered through filter paper into to a 2 L flask. The solids werecollected and washed with DCM (250 mL) into the flask and the flask wascovered with a septum and N₂ balloon. Tea (35 mL) followed by DMAP(1.284 g) and TES-Cl (˜30 mL, 3.5 eq) were added to the solution andstirred. Additional TES-Cl (15 mL) and TEA (20 mL) were added, and after6 hours HPLC indicated the reaction had gone to completion.

The reaction was then quenched by the addition of EtOH (25 mL). Thelayers were separated and the organic layer was washed with saturatedNH₄Cl (˜500 mL) and dried over Na₂SO₄ and concentrated. A flash columnwas packed with silica gel and wet with 8:2 heptane/IPAc (1.5 L). Thesolids were dissolved in 8:2 heptane/IPAc (250 mL) and filtered toremove solids that would not dissolve. This solution was concentrated to˜100 mL and applied to the column. The column was eluted with 8:2heptane/IPAc and fractions collected. Fractions with product were pooledand concentrated to give foam of Formula 39.

Formula 39 was then oxidized to form Formula 40 according to thefollowing reaction:

Here, solid Na₂SO₄ was added to a solution of Formula 39 (24.45 g, 24.0mmol) and 4-methyl morpholine N-oxide (10.1 g, 84 mmol) in DCM (340 mL)to assure that the reaction was dry. The mixture was stirred for 1 hourand then filtered through 24 cm fluted filter paper into a 2 L 3-N roundbottom flask. The Na₂SO₄ solids were washed with DCM (100 mL) into theflask. Molecular sieves (6.1 g, 15 wt %/g) were added to the solutionand stirring was begun. TPAP (1.38 g) was added and the reaction wasallowed to stir under a N₂ blanket. Samples were taken periodically forHPLC. Additional TPAP (0.62 g) was added after 2 hours and again (0.8 g)after 15 hours. The reaction mixture was applied to a pad of silica gel(86 g), wet with 8:2 heptane/IPAc and eluted with IPAc. The fractionswere collected, pooled and concentrated to an oil. 4-Methyl morpholineN-oxide (5.0 g) and DCM (100 mL) were added and stirred. Na₂SO₄ (13 g)was added to the mixture and it was filtered through filter paper. TheNa₂SO₄ solids were washed with DCM (45 mL) and molecular sieves (5 g)and TPAP (1.03 g) were added. After 45 minutes, more TPAP (1.05 g) wasadded. A pad of silica gel was prepared and wet with 80:20 Heptane/IPAc.The reaction mixture was applied to the pad and eluted with IPAc.Fractions were collected and those fractions containing product werepooled and concentrated to give an oil product of Formula 40.

Next, Formula 40 was reduced according to the following reaction to formFormula 41.

NaBH₄ (365 mg, 6 eq) was added to a stirred solution of Formula 40 (1.6g) in EtOH (19 mL) and MeOH (6.5 mL) cooled in an ice-water bath. After1 hour, the reaction mixture was removed from the ice-water bath and at2 hours, the reaction was sampled for HPLC, which indicated the reactionhad gone to completion. The reaction mixture was cooled in an ice-waterbath and a solution of NH₄OAc in MeOH (15 mL) was added followed by theaddition of IPAc (50 mL) and H₂O (20 mL). It was mixed and separated.The organic layer was washed with water (20 mL) and brine (10 mL), asecond time with water (15 mL) and brine (10 mL), and then twice withwater (2×15 mL). It was dried over Na₂SO₄ and placed in the freezerovernight. The following morning a sample was taken for HPLC and thereaction was dried and the organic layer was concentrated on therotovap. It was placed in the vacuum oven to give a foam product ofFormula 41.

Formula 41 was next acylated to form Formula 42 according to thefollowing reaction:

TEA (5.8 mL, 41.5 mmol), Ac₂O (2.62 mL, 27.7 mmol) and DMAP (724 mg, 5.5mmol) were added to a solution of Formula 41 (14.1 g. 13.84 mmol)) inDCM (50 mL). The reaction was stirred and sampled for HPLC periodically.After 18.5 hours, additional TEA (1.5 mL) and Ac₂O (1 mL) were added. At19 hours, HPLC indicated the reaction had gone to completion. Thereaction mixture was diluted with IPAc (300 mL) and poured into 5%HaHCO₃ (100 ml). It was then stirred, separated, and the organic layerwas washed with water (100 mL), saturated NH₄Cl (2×100 mL), water (3×50mL) and brine (50 mL) and then filtered through Na₂SO₄. The mixture wasconcentrated to give a foam product of Formula 42.

Next, Formula 42 was converted to a compound of Formula 43 according tothe following reaction:

A quantity of Formula 42 (3.0 g, 2.829 mmol) was weighed into a 100 mLflask. Next, DCM (24 mL) followed by MeOH (6 mL) were added to the flaskat room temperature. Stirring of the mixture began under N₂ and CSA(0.0394 g, 0.17 mmol) was added. After 4 hours LCMS indicated theproduct had formed. 5% NaHCO₃ (15 mL) was added to the reaction mixture;it was shaken vigorously and then added to a separatory funnel. Thereaction flask was rinsed into the separatory funnel with 5% NaHCO₃ (25mL) and, thereafter, the reaction mixture was shaken and the layers wereseparated. The organic layer was washed with brine, dried over Na₂SO₄,and concentrated. MTBE (3×25 mL) was added and the reaction mixture wasconcentrated to dryness after each addition to finally give 3.7068 gfoam. The foam was dissolved in MTBE (10 mL) and stirred. Heptane (50mL) was slowly added to the reaction solution and solids began to formimmediately. The solids were vacuum filtered and rinsed with heptane(720 mL). The solids were collected and dried in a vacuum oven at 40° C.to give Formula 43.

Formula 43 was then converted to Formula 44 in the following reaction:

A solution of Formula 43 (2.1 g, 2.52 mmol) in DCM (10.5 mL) was stirredat room temperature. Next, 3,3-dimethoxy-1-propene (2.03 g, 17.7 mmol)followed by CSA (0.035 g, 0.15 mmol) were added to the solution. Afterthe solution was stirred for 3.5 hours, LCMS indicated the reaction hadgone to completion. The reaction was diluted with DCM (25 mL) and addedto a separatory funnel with 55 mL 5% NaHCO₃ solution. The layers wereseparated and the aqueous layer was washed with DCM (25 mL). The twoorganic layers were combined, washed with brine, dried over Na₂SO₄ andconcentrated. A flash chromatography column was packed with silica geland wet with 50:50 MTBE/heptane (1000 mL). The reaction mixture wasdissolved in MTBE (10 mL), loaded on the column and eluted with 50:50MTBE/heptane. The fractions were collected, pooled, concentrated anddried in a vacuum oven at 50° C. to give product of Formula 44.

IX. Alternate Sidechain Coupling Reaction

As illustrated above in the second reaction step of the alternativeprocess of forming 7,9 acetal linked analogs of 9,10-αα OH taxanes, theC7,C10 di-CBZ 10-deacetylbaccatin Ill of Formula 35 was coupled with asidechain of Formula 36 to form Formula 37. The present inventionfurther contemplates the coupling of an alternative sidechain to Formula35. The alternative sidechain of Formula 45 that is contemplated has thefollowing structure:

Formula 45 may be formed from the structure of Formula 36 (above)according to the following reaction:

Here, the BOM-acid, Formula 36, (3.8 g, ˜10.0 mmol) was dissolved in DCM(30 mL), stirred and cooled in an ice-water bath at 0° C. under N₂. DCM(2 mL) and diethyl sulfur trifluoride (1.575 g, 20.0 mmol) were bothadded to this solution and the reaction was stirred for 4 hours. Thetemperature increased to about 10° C. LCMS indicated the reaction hadgone to completion. H₂O (50 mL) and DCM (50 mL) were added and thereaction mixture was transferred to a separatory funnel. The layers wereseparated and the organic layer was washed with H₂O (50 mL) and brine(50 mL), dried over Na₂SO₄ and concentrated yielding product of Formula45.

Next, Formula 35 was coupled with a sidechain of Formula 45 resulting inproduct of Formula 46 according to the following reaction:

Here, Formula 35 (0.2 g, 0.246 mmol) and DMAP (0.5 g, 4.1 mmol) wereweighed into a pear shaped flame-dried flask purged with N₂. Anoven-dried reflux condenser, purged with N₂, was placed on top of theflask and it was put in an oil bath heated to 75° C. The BOM acylfluoride, Formula 45 (0.5 g, 1.31 mmol), in toluene (1 mL) was added tothe flask and the temperature increased to 85° C. Stirring continuedunder N₂ for 5.5 hour to give product of Formula 46.

Accordingly, the present invention has been described with some degreeof particularity directed to the exemplary embodiments of the presentinvention. It should be appreciated, though, that the present inventionis defined by the following claims construed in light of the prior artso that modifications or changes may be made to the exemplaryembodiments of the present invention without departing from theinventive concepts contained herein.

1.-32. (canceled)
 33. A method for the treatment of cancer in a cancerpatient, said cancer selected from the group consisting of OvarianCarcinoma, Breast Cancer, Neuroblastoma and Squamous Cell Carcinoma, themethod comprising: administering to the cancer patient a pharmaceuticalformulation comprising a taxane derivative and a pharmaceuticallyacceptable carrier, said taxane derivative having an acetal bridgebetween the hydroxyl groups at the 7- and 9-ring positions and having a,a stereochemistry at the 9- and 10-ring positions.
 34. The method forthe treatment of cancer according to claim 33, wherein said cancer isOvarian Carcinoma.
 35. The method for the treatment of cancer accordingto claim 33, wherein said cancer is Breast Cancer.
 36. The method forthe treatment of cancer according to claim 33, wherein said cancer isNeuroblastoma.
 37. The method for the treatment of cancer according toclaim 33, wherein said cancer is Squamous Cell Carcinoma.